1. Field of the Invention
This invention relates generally to compositions that impart stain resistance to substrates that have been treated with the compositions. The invention further relates to methods for imparting stain resistance to the substrates by treating them with these compositions, and to the articles that have been treated with the compositions. More specifically, this invention relates to the use of organoborane amine complexes to provide compositions that impart stain resistance, as well as to methods for imparting stain resistance using these complexes, and to articles (especially carpet) that have been treated with compositions that incorporate these complexes.
2. Description of the Related Art
Fibrous substrates (e.g., fabrics, textiles and carpets) are often treated with compositions that provide stain resistance. These compositions, sometimes referred to herein as stainblocking compositions or stainblockers, prolong the useful life of fabrics and textiles by rendering them more resistant to staining by food and other materials. One well-known use of stainblockers is for treating carpet. It has been reported that most carpet is replaced because of unsightly stains rather than physical wear.
Rendering nylon carpet resistant to staining is particularly important. Nylon fiber is commonly used to manufacture carpet because it has many desirable qualities. It is durable, comfortable and provides warmth. It can be made into carpet having a wide variety of textures, colors and patterns. However, nylon carpet can be readily, if not permanently, stained by various natural and artificial colorants found in foods such as coffee, mustard, wine and soft drinks. An artificial colorant for food known as "Red Dye No. 40" (sometimes called FD&C Red Dye No. 40 or C.T. Food Red 17) has been reported to actually dye and, therefore, permanently stain, nylon carpet fiber within minutes after a food containing this dye has been spilled on the carpet.
Consequently, there has been considerable effort to provide compositions that will impart stain resistance to nylon fiber carpet. For example, U.S. Pat. No. 4,822,373 (Olson et al., assigned to Minnesota Mining and Manufacturing Company) discloses a method of providing fibrous polyamide substrates (such as nylon carpet) with resistance to staining by acid colorants. A composition comprising (a) a partially sulfonated novolak resin; and (b) polymethacrylic acid, copolymers of methacrylic acid, or combinations thereof is applied to the carpet.
A stain resistant composition for polyamide fibers that is prepared by polymerizing an .alpha.-substituted acrylic acid or ester in the presence of a sulfonated aromatic formaldehyde condensation polymer is described in U.S. Pat. No. 5,061,763 (Moss, III et al., assigned to Peach State Labs, Inc.). Also described in this patent is a stain resistant composition prepared by (1) esterification of an acrylic acid with a sulfonated hydroxyaromatic compound followed by (2) polymerization of the acrylic acid.
U.S. Pat. No. 4,892,558 (Blyth et al., assigned to Monsanto Company) describes nylon fibers that resist staining by acid dye colorants. The nylon fibers are spin finish coated with a stainblocker that can be prepared by the condensation of formaldehyde with one or more phenols.
U.S. Pat. No. 4,963,409 (Liss et al., assigned to E. I. du Pont de Nemours and Company) describes imparting stain resistance to polyamide substrates by using sulfonated phenol-formaldehyde products in which a portion of the free hydroxyl groups have been acylated or etherified. U.S. Pat. No. 5,001,004 (Fitzgerald et al., also assigned to Dupont) discloses polyamide textile substrates treated with a non-sulfonated stain-resistant composition comprising hydrolyzed ethylenically unsaturated aromatic/maleic anhydride polymers. A composition that is said to impart stain resistance to polyamide textile substrates and containing a sulfonated phenol-formaldehyde condensation product, and a hydrolyzed polymer of maleic anhydride and one or more ethylenically unsaturated aromatic monomers is described in U.S. Pat. No. 4,883,839 (Fitzgerald et al., also assigned to Dupont).
U.S. Pat. No. 4,865,885 (Herlant et al., assigned to Crompton & Knowles Corporation) describes an agent that is reportedly useful in preventing nylon fibers from being permanently stained by food colors. The agent is obtained by adding a sulfonated phenol-formaldehyde or naphthol-formaldehyde to an anionic surfactant.
U.S. Pat. No. 5,073,442 (Knowlton et al., assigned to Trichromatic Carpet, Inc.) discloses a method of enhancing the soil-and/or stain-resistant characteristics of polyamide fabrics by applying a solution containing, in a variety of combinations: sulfonated phenolic resins, sulfonated aromatic compounds, compounds of sulfonated phenolics; and aldehydes, modified wax emulsions, fluorochemicals, acrylics, and organic acids of low molecular weight.
However, there is still a need for stainblocking compositions having even improved properties. It would be advantageous if such compositions could provide either enhanced stain resistance at concentrations of stainblocker that are equivalent to those conventionally used (as this would yield improved performance), or equivalent performance at concentrations of stainblocker that are less than conventionally used (as this could reduce manufacturing costs since less stainblocker would be needed).
It would also be advantageous if the stainblocking compositions retained their effectiveness after the carpet has been cleaned. It has been reported that steam cleaning carpets can reduce the efficacy of a previously applied stainblocking composition. Consumer-applied stainblocking treatments that are available to revitalize carpet provide only a partial solution because commercial treatments are usually applied by the carpet mill in a steaming process that is difficult for consumers to effectively duplicate. Thus, a stainblocking composition that can be easily and effectively applied by consumers would be highly desired.
Many stainblocking compositions, in order to achieve maximum effectiveness, are applied at a very low pH of about 3 or less (i.e., highly acidic conditions). However, the manufacturer of the stainblocking composition will often ship it to an end user (e.g., a carpet mill) at a pH of about 4 or higher so as to reduce the corrosive effects that highly acidic compositions can have on the shipping containers (e.g., drums, tank cars, etc.). This not only complicates the handling of the stainblocking composition, it also raises the cost of manufacturing and using it. The manufacturer of the stainblocking composition will often add an alkaline material to raise the pH so that the stainblocking composition can be more easily shipped. The user then acidifies the stainblocking composition so that it can be applied with the best effectiveness. However, the user's resulting waste stream also becomes highly acidic, and frequently alkali must be added to the waste stream so that it can be discharged into a municipal sewer system.
Thus, it would also be advantageous to have a stainblocking composition that could be effectively used at a higher pH. This would not only provide a more environmentally acceptable composition, it would also reduce or eliminate the need for special handling requirements before shipping, using or disposing of the stainblocking composition.